1. Field of the Invention
The present invention relates to a method for reading or writing data on magnetic tape using a multiple channel head which is transversely movable with respect to the recording tape. The present invention also relates to magnetic head mechanisms, particularly with respect to a multiple channel head controlled by a servoing system.
2. Description of the Prior Art
Data recording cartridges containing magnetic tape and recorders adapted for their use are disclosed and claimed in U.S. Pat. No. 3,692,225 (von Behren). The recorders adapted to use such data cartridges originally employed fixed multitrack heads for accessing the tracks on the magnetic tape in the data cartridge. These fixed, multitrack heads were complex, expensive and difficult to maintain in proper alignment.
To eliminate the multitrack heads, U.S. Pat. No. 4,313,143 (Zarr) disclosed a head positioning mechanism by which a single track head could be transversely positioned with respect to the width of a magnetic tape having a plurality of parallel tracks. The system disclosed in Zarr works satisfactorily but a different system was needed when the data cartridges and recorders were miniaturized. The type of head positioning mechanism which works satisfactorily in a smaller recorder is disclosed in U.S. Pat. No. 4,750,067 (Gerfast). Gerfast uses a stepper motor to accurately move the head in a direction transverse to the tape.
Even with the head positioning mechanism of Gerfast, the number of tracks on the magnetic tape which can be accessed by a head is limited by the accuracy of head positioning possible with a stepper motor system and the variability of tape position within a cartridge as the tape crosses the head.